This study will investigate the effects of a dopamine-beta hydroxylase blocker, fusaric acid on psychological state and on recorded sleep in twenty-four normal male subjects. The design will involve a balanced intra-subject (crossover) comparison of three drug conditions in each subject. Each subject will be studied under the following three conditions: 1) fusaric acid (600 mg) in the morning, followed by L-DOPA (500 mg) three times later in the day; 2) placebo in the morning, followed by L-DOPA (500 mg) three times later in the day; 3) placebo in the morning, followed by placebo three times later in the day. Effects will be studied by means of psychiatric interviews, self-report forms, psychological tests, vigilance tests, waking EEG and all-night polygraphic sleep recordings.